That performance resurfaced on CNN’s iReport and then circulated widely online. It included lyrics calling for the death of American troops serving in Iraq, not long after news of the brutal slaying of a South Korean hostage by Iraqi insurgents — an incident which sparked anti-American sentiment in South Korea.

In his apology, PSY said his performance had been emotionally charged and was a response to events in the war in Iraq.

“I understand the sacrifices American servicemen and women have made to protect freedom and democracy in my country and around the world,” he said in a statement.

He said the song “was part of a deeply emotional reaction to the war in Iraq and the killing of two Korean schoolgirls that was part of the overall anti-war sentiment shared by others around the world at that time.”

The girls were struck and killed by a U.S. military vehicle.

PSY continued: “While I’m grateful for the freedom to express one’s self, I’ve learned there are limits to what language is appropriate and I’m deeply sorry for how these lyrics could be interpreted. I will forever be sorry for any pain I have caused by those words.

“While it’s important that we express our opinions, I deeply regret the inflammatory and inappropriate language I used to do so.”

The lyrics of the song, titled “Dear America,” were written by the South Korean rock band N.E.X.T., and PSY was one of three performers rapping out the lyrics on stage.

The lyrics were posted on an unvetted CNN iReport in October. The English translation of the Korean lyrics has picked up steam online since then, drawing thousands of views, and then exploding on blogs and social media this week. CNN reached out to the iReporter who brought attention to PSY’s anti-American lyrics, but did not receive a response.

CNN was able to translate the lyrics as saying,” Kill those f–ing Yankees who have been torturing Iraqi captives and those who ordered them to torture,” and going on to say, “Kill them all slowly and painfully,” as well as “daughters, mothers, daughters-in-law and fathers.”

PSY is scheduled to perform as planned with stars such as Diana Ross and Demi Lovato at the event, Christmas in Washington, said TNT, which is airing the event. President Barack Obama is also planning on attending the event.

The lyrics led to a petition on whitehouse.gov demanding that he be dropped from the concert, as conservative websites picked up the story. But the petition was deleted later in the day. The White House website claimed that it violated terms of participation.

Commenters on the original CNN iReport responded with varying viewpoints on the lyrics.

Some expressed outrage over the Korean pop star’s alleged call for the slaying American troops. Commenter shin000 said on October 31: “Whatever the reason is, the fact that PSY insulted American Army and their family is changeless. He sang this song because of that accident and public opinion?”

Others praised PSY for speaking up and expressing his anti-war sentiments. Commenter SavvyMike said on October 30: “As an American, this makes me like Psy even more. Glad to see he has the balls to call out America when we are doing evil.”

Other commenters lashed out at the iReporter, saying that he misrepresented PSY in his iReport contribution. Commenter jsong9172 said on October 30, 2012: “He is criticizing the US Army, not the country. Do a thorough background research before you scribble something otherwise you’d ruin one’s life.”

After the lyrics from the 2004 performance surfaced, there was an often vitriolic response on Twitter:

“So Mr. ‘Gangnam Style’ @psy_oppa made a song before about America and how all U.S. soldiers should be killed….guy should flee the US now,” said @TheOfficialTate.

Fashion publicist/reality star Kelly Cutrone said his “words against the women in my country” were “disgusting,” and referred to him as a “poseur faker freak.”

@eclecticbrotha defended him saying, “Oh look, we’re supposed to hate Psy because he once joined protests against American imperialism.”

As for PSY’s handling of the criticism, Matt J. Duffy, a journalism teacher from Atlanta, tweeted, “His statement is lesson in good crisis PR.”

It’s unclear what the fallout of the revelation of these anti-American lyrics will be.

But it has us wondering — what do you think the consequences should be? Should a rapper be held accountable for what he said in 2004? Let’s talk about it in the comments on this story. You can be sure we’ll continue this conversation on CNN for the next few days.